.overlay{
    position:fixed;
    top:0;
    left:0;
    right:0;
    bottom:0;
    background:rgba(0,0,0,.3);
    z-index:1000;
}

.dialog-body{
    position:fixed;
    width:200px;
    height:150px;
    z-index:1001;
    left:50%;
    top:50%;
    margin-left:-100px;
    margin-top:-75px;
}